If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.

Help! Can't solve SES, rough idle problem!

I have a '95 740il that has been running poorly and the SES light comes on in certain cases. When the temperature is above 30 degrees the car runs fine but still has fault codes for the MAF and Lambda control #1 (No SES light). When the temp is between 15 and 30 I get the SES light. When the temp falls below 15 I get O2 sensor #1 and lambda #2 codes as well and the car idles rough and sometimes stalls. Within the past year I have replaced the Cats (the new cats aready sound like marbles), the O2 sensors, the MAF sensor, the intake manifold gaskets, the spark plugs, the valve cover gaskets and even the gas cap. I have checked the ICV and it seems fine. What am I missing? Any ideas on what to try next? Could it be the computer? At this point it might be easier and cheaper just to move to a warmer climate but I can't get my wife to go for that. Please help, it is driving me nuts. Thanks.

Re: Help! Can't solve SES, rough idle problem!

Follow up - I replaced the CPS and cleaned the ICV. I am still getting SES and rough idle when the outside temp is below 15, even when the engine warms up. The codes are for O2 sensors 1 & 2 and Lambda Control 1. I am no longer getting the MAF fault. Anybody have any other ideas?

Re: Help! Can't solve SES, rough idle problem!

I'm dealing with a similar issue right now and haven't gotten much help. My SES light just came on after cleaning and reinstalling the Idle control valve. I can tell you (lots of experiance on older BMWs) that you can usually tell if the ICV is sticking by shaking it...it should 'rattle' freely. After cleaning mine idle improved. Now mine only idle poorly (stumbling) when warmed up under load. Checking the codes this week. I'm new to these cars and it looks like a long learning curve.

Re: Help! Can't solve SES, rough idle problem!

I have a similar problem. I've cleaned my idle control valve, and it shakes freely. New MAF. I'm going to electrically test the idle control valve next. I understand that I should get 40 ohms across the outside terminals, and 20 ohms from outside to center terminals. Also, should be able to see a smooth change in resistance while moving the valve open and closed, with no dead spots.

I'm hoping to get to that tomorrow night. Have you had any change in your situation?

Re: Help! Can't solve SES, rough idle problem!

I have had some change. After I cleaned the ICV and replaced the top CPS it runs a little better. I no longer get the MAF fault. Now I just get the lambda sensor and O2 sensor faults. Weather is warmer so that seems to have helped. any other ideas on what to try?

Re: Help! Can't solve SES, rough idle problem!

Sorry... but you need to go back to the drawing board... in spite to have check this and the other determining that nothing wrong with idle control valve and other components... unless you have sophisticate equipment to check condition of those electronic components...

CAVEAT

Caveat: most likely a few have an understanding how everything works on modern cars… I have mentioned several times upstream… down stream, which may be misunderstood. If so, there are engine components which may or may not generate an error codes such a pulse generator [also known as knock sensors], and the downstream error code would be a deficient catalytic converter, and the problem is not the the catalytic converter. I have talked about engine management components on previous postings... not understood because lack of facts as to what engine management or transmission management is, and all of the problems do to automation [computers], and lack of sophisticated equipment to measure faults or weakness on the system. In essence, cars lack of instrumentation which could provide failure reports as on modern airplanes do.

Re: Help! Can't solve SES, rough idle problem!

I'm having a similar Service Engine Soon (SES) problem also. My codes say Mass Air Flow/Meter. I bought a new MAF cheaply on ebay and it doesn't even have any part # on it and my problem persists. Wondering if it is something as simple and cheap as the O ring p/n 13711731893 or the flat rubber ring p/n 13711736195 that wrap the MAF letting air spin? I've read about Mass Air Flow/Meter from rover m62 4.4 p/n B3130-139283 being identical to eom and alot cheaper in cost. Is this the case? $134 auothausaz vs. Bosch $188 p/n 0280217814 autohausaz vs. stealer $310. hmmm. Advice? thx.

Re: Help! Can't solve SES, rough idle problem!

I had a problem with rough idling specially when the engine is cold. check engine light keeps coming out. Finally a sensible mechanic here in orange county ca looked at it. He plugged in smoke to one of the vaccum hoses and smoke came out of the air intake manifold. Changed the seals and everything worked out well.

Testing coils...

Coil test can be done using an ohmmeter, check the resistance between the side terminals of the coil. Do this with all of the wires to the coil disconnected.

You should see 0.75 to 0.81 ohm of resistance. Then check the resistance between either side terminal and the center high tension terminal. The reading should be 10,000 to 11,000 ohms. Any significant deviation from these numbers would indicate that the coil is defective.

Re: Yea, the Rover or VW MAF will work in some of

romac, I will try to test the coils. How did you determine that you had a bad coil? The car ran fine during the warm weather. Now that it is cold I am having the same problems. When the engine is cold the SES light comes on and I get codes for side 1 O2 sensor and side2 Lambda control. The engine runs rough when idling and almost stalls (white/blue exhaust smoke). At higher rpms it seems to run fine. Once the engine is hot and I reset the codes it runs better. The SES light only comes on when I am at idle. It goes off when I accelerate. Any new ideas?

Re: Testing coils...

Claudio, Could you elaborate a little further on the coil test? I tested the coils as I think you described them and got readings between .4 and .6 on the outside terminals and between .6 and 1.4 on one terminal and the center post. I can't believe all my coils are bad. I must be doing something wrong.

Sounds like it's running rich during winter due to

excessive fuel from "cold start"- check the thermosensor on top of the thermostat or WP.

Older BMW has the same problem: cold condition, DME sense temp then inject extra fuel into engine through an add'l cold start injector to pump extra fuel. Thermo sensor is bad so it can't sense temp and determine when to shut off extra fuel. Another clue is the smoke, prob smell like rich mixture.

Re: Sounds like it's running rich during winter due to

Peter, thanks for the suggestion, however it looks like the '95 with the M60 engine does not have the sensor the M62 has. My car does not have one and the new housing for sale on the web do not show the plug. The TIS and the ETK don't show one either but it is not very detailed. Any other suggestions?